Cancer surveillance provides a quantitative portrait of cancer in a defined population (in this case the residents of Nova Scotia). Core functions of cancer surveillance include the measurement of cancer incidence, morbidity, survival, and mortality of persons with cancer. Cancer surveillance tells us where we are in the effort to reduce the cancer burden and also generates observations that form the basis for cancer research and interventions for cancer prevention and control. (National Cancer Institute, National Center for Health Statistics, Centers for Disease control and Prevention, American Cancer Society, North American Association of Central Cancer Registries, 2001).

Cancer Care Nova Scotia (CCNS) staff will often receive questions from the public or other stakeholder groups that reflect a need to understand cancer burden and the impact on Nova Scotia communities. The public asks questions such as "how many people get cancer in Nova Scotia?" or, "What kinds of cancer are people diagnosed with?" “Who, where, when” types of questions are the basis for descriptive cancer epidemiology which attempts to describe the occurrence of the disease in the population, observing differences, for example, by sex, age group, geographical area, and between time periods.

CCNS operates a cancer surveillance and epidemiology unit (SEU) to assist in answering these types of questions to support cancer system management. The SEU also provides expertise and data for various types of epidemiological research. Key cancer system activities carried out by the SEU include: